Fatigue Behavior of SiC Particle Reinforced A2024-T6 Aluminum Alloy under Sinusoidal and Repeated Impact Load Conditions

摘要

Fatigue tests and fatigue crack growth tests were conducted under sinusoidal tensile load using a sintered aluminum alloy A2024-T6 reinforced with 20 percent SiC particles in volume. Monolithic specimens of aluminum alloy A2024-T6 were used to obtain the reference data. Fatigue tests under repeated impacts were also conducted to examine the effect of the impact load on the fatigue strengths of both materials. It was found that the particle reinforced aluminum alloy (PRM) has a higher fatigue strength and a lower resistance to the fatigue crack growth than the monolithic aluminum alloy. Re-aged monolithic aluminum alloy with higher hardness number was tested to find the effect of the hardness on the fatigue strength, but no difference of the strengths was observed between the original A2024-T6 specimens and re-aged ones. As one of the other factors, the X-ray residual stresses were measured for both materials, and considerable compressive stresses were observed in the PRM matrix. Therefore, it was concluded that the compressive stresses around SiC particles suppress the initiation of fatigue cracks and lead to the higher fatigue strength of the PRM. Additionally, it was found that the fatigue strengths of both materials under repeated impacts were lower than those under sinusoidal loads.